The state-of-the-art quantum control in systems such as photonics [1]}, [2]}, [3]}, cold atoms [4]}, [5]}, [6]}, [7]}, or trapped ions [8]}, [9]}, [10]} offer unprecedented access to the rich dynamics and exotic phenomena in open quantum systems that undergo particle or energy exchange with their environment.
A non-Hermitian description applies therein, for instance, by imposing post selection [11]}, [12]}, [13]}, [14]}, [15]}, or by mapping the density-matrix dynamics to an enlarged Hilbert space [16]}, [17]}, [18]}, [19]}.
The resulting non-Hermitian physics provides an unconventional perspective of open systems, and has attracted extensive interest in recent years.
Dictated by a non-Hermitian effective Hamiltonian, exotic spectral or dynamic properties, such as the parity-time symmetry [20]}, [21]}, enhanced sensing [22]}, [23]}, [24]} and topological transfer [3]}, [7]}, non-Hermitian topology [27]}, [28]}, [29]}, [30]}, [31]}, [32]} and so on, have been systematically studied and experimentally confirmed in a wide range of physical systems.
